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A sample contains two radioactive substances A and B in the ratio of 4 : 1 . If their half lives are 24 and 16 hours respectively , then after two days what will be the ratio of A and B?

A sample contains 0.1 gram-atom of radioactive isotope ._(Z)^(A)(t_(1//2)=5 days) How many number of atoms will decay during eleventh day? [N_(A)= Avogradro's number]

A sample containing only CaCo_(3) and MgCo_(3) is ignited to CaO and MgO. The mixture of oxides produced weight exactly half as much as the original sample. Calculate the percentages of CaCO_(3) and MgCO_(3) (by mass) in the sample.

(A)Same reactants give different products with different catalysts.(R ) Catalyst is highly specific or selective.

(A) : Same amount of copper can be deposited from cupric salt and cuprons salt using one faraday. (R): One faraday can deposite one equivalent of copper. The correct answer is

(A): Same chemicals may be used as antiseptics as well as disinfectants. (R): A chemical which destroys micro organism can be used as an antiseptic in higher concentration and as disinfectant in lower concentration.

A salt 'X' is dissolved in water (pH = 7), the resulting solution becomes alkalinein nature. The salt is made of

A salt X gives white precipitates with lead acetate solution, insoluble in hot water and nitric acid. The salt X most probably contains:

A salt which gives CO_2 with hot H_2SO_4and also decolourises acidified KMnO_4 on warming is :

A salt which gives brown vapours with cone. H_2SO_4and turns water yellow is:

A salt when heated with H_(2)SO_(4) librates violet gas which turns starch paper blue, salt may be

A salt solution reacts with some drops of chloroform and the mixture is shaken with chlorine water. The chloroform layer becomes violet. Salt solution contains:

A salt was first heated with dilute H_2SO_4 and then with concentrated H_2SO_4, no action was observed in either case. The salt must be

A salt solution reacts with some drops of chloroform and the mixture is shaken with chlorine water. The chloroform layer becomes violet. Salt solution contains.

A salt solution is treated with chloroform drops. Then it is shaken with chlorine water. Chloroform layer becomes violet, solution contains.

A salt solution is treated with chloroform drops and is shaken with chlorine water. Chloroform layer becomes violet solution contains:

A salt solution of Cd^(2+) in dilute HCl, on treatment with a solution of BaCl_(2) gives a white precipitate, which is insoluble in concentrated HNO_(3). Anion in the salt may be :

A salt solution is acidified with dil. HCl and BaCl_2 solution is added. A white ppt. is formed. The salt contains

A salt producing hydrocarbon among these compounds is

A salt on treatment with dil. HCl gives a pungent smelling gas and a yellow precipitate. The slt gives green flame when tested. The salt solution gives a yellow precipitate with potassium chromate. The salt is

A salt on reaction with dil. H_2 SO_4 gives a reddish brown gas. The salt is

A salt of sulphurous acid is called:

A salt MX has NaCl type lattice in which r is the minimum distance between M^(z+) and X^(z-). Each M^(z+) ion is surrounded by

A salt of NaX overset(MgCl_(2))rarr" white ppt." on boiling. Thus, anion X is :

A salt of 3d metal gave a white precipitate with NH_(4)OH, but dissolves in excess NH_(4)OH. Name the 3d metal.

A salt is heated first with dil. H_(2)SO_(4) and then with conc. H_(2)SO_(4). No reaction takes place. It may be

A salt imparts a yellow colour to a borax bead in an oxidising flame. What would be the colour of the bead in a reducing flame

A salt gives white residue in charcoal cavity test but in cobalt nitrate test it gives pink mass. It represents :

A salthaving BO_(3)^(3-) on burning with cone H_(2)SO_(4) gives …. Edge flame

A salt containing water of crystallization gave the following percentage composition : Mg = 9.76 , S = 13.01 , O = 26.01 and H_(2)O = 51.22 Calculate the simplest formula. (At. Mass of Mg = 24)

In a system.A(s)+B(g)+ Heatrarr 2C(s)+2D(g)equilibrium is established.The pressure of B vapour is doubled to re - stablish the equilibrium.The factor by which D is changed is :

A rubber balloon permeable to hydrogen in all its isotopic forms is filled with deuterium (D_(2)) and then placed in a box containing pure hydrogen. Will the balloon expnad or contract or remains as it is ?

A: Roasting process is involved in the metallurgy of Cu from Malachite ore. R: Roasting is the process of heating the ore in absence of air.

A reversible reaction H_(2)+Cl_(2)hArr2HCl is carried out in one litre flask. If the same reaction is carried out in two litre flask, the equlibrium constant will be

A reversibleheatengine A(basedon carnot cycle ) absorbs heat froma reservoirat 1000 K and rejects heat to a reservoirat T_(2) . A secondreserviour at T_(2) and rejects energy to areservoirat360 K .If the efficienciesof engines A and Bare thesame then the temperature T_(2)is .

A reversible chemical reaction having two reactant is in equiliberium. If the concentrations of the reactants are doubled then the equiliberium constant will :

A reversible chemical reaction haiving two reactants in equilibrium. If the concentrations of the reactants are doubled, teen the equilibrium constant will

A resucing agent is a substance which can

(A) Relation between (A)&(B) is :

(A) Reimer Tiemann reactions of phenol with chloroform in alkali produce salicylade-hyde as major product(R) The reaction involves in the formation of dichloro carbene as intermediate

(A) Reimer-Tiemann reaction of phenol with C Cl_(4) in NaOH at 340K gives salicylic acid as the major product. (R ) The reaction occurs through intermediate formation of dichlorocarbene.

A regular tetrahedron is obtaining during _____hybridisation in alkanes.